The camera operator gave us a wonderful peek at the eggs when Mr. North left this morning. The hatching window is larger, and we can see the outer shell, the inner membrane, and the eaglet moving around inside the egg. I’m not sure whether this is DN19 or DN20: we saw the first pip at 12:03 PM and the second one at 1:18 pm, which means these two eaglets will probably be hatching very close together! It wasn’t especially warm when DNF laid her first egg and she laid the eggs roughly three days apart, so how did she delay development of the first egg?
While we usually associate incubation with warming eggs – especially in an Iowa February! – birds can also cool them. Bald eagles regulate egg temperature by adjusting blood flow to their brood patch, shading or standing over their eggs instead of sitting on them, and repositioning the eggs and themselves to apply or decrease heat as needed. Even in a cold Iowa winter, a skilled, experienced bird can delay early embryonic development without harming her eggs. We’ll have to look through our data and see whether more experienced parents are likely to have eaglets that hatch closer together.
If you missed our blog on hatch, learn more about the process here! https://www.raptorresource.org/2025/03/18/announcing-hatch-watch-at-decorah-north/
The Raptor Resource Project